Steps to rebuilding a carb from poor to thorough
Below are some steps to rebuilding a carburetor, from basic and poor, getting better, to doing a really complete and effective job. How good a job do you need to do? What is necessary? How bad is your carburetor?
All of these have been mentioned on here before, I'm just trying to put them together on one post and consolidate them and add my experiences.
You must always use fresh gas, less than 60 days old, and IMO preferably less than 30 days old. After these days, use it in your car. I buy gas for my snowblower a few days before we are likely to get snow but I don't put it in nor do I start it! My snowblower gas tank and carburetor is empty of gas. If it's in the season, I add StaBil to the gas, some add Seafoam, both are fuel stabilizers, the latter a marine fuel stabilizer. In the beginning of the season I also add just the recommended amount of carburetor cleaner to the gas. My favorites are Lucas, Gumout, Chevron Techtron, and Gunk.
You have to understand that gasoline has volatile ingredients that evaporate as time progresses and thickens, as this is going on, old gas develops a hard varnish on the metal, especially inside the orifices and passageways.
Cleaning a carburetor in order of effectiveness
Method 1 - materials needed: spray carburetor cleaner, folding set of welding torch tip cleaners $3 - a must! the tip cleaners are abrasive similar to a round file
Take the carburetor off the engine and apart, hoses off, fuel bowl off, needle valve removed, and any adjustment screws removed, and spray the cleaner in every opening. Let sit for a bit but keep in mind the carb cleaner evaporates at a high rate. Put the correct size tip cleaner in every orifice.
How well does this work? How bad is your carburetor? IMO, this is not the way to do it, what a waste of time, though I do admit at times it does work.
Method 2 - materials needed: same as above (spray carburetor cleaner, welding torch tip cleaners) AND 1 small welch plug!
You will be more successful with Method 2 than 1 because it incorporates the removal of the small side welch plug found on the outside side of the carburetor. There are 3 small holes/passageways under the welch plug that control the idling and surging of the engine. You probably won't find any gunk behind the welch plug but you need to remove the plug in order to access the 3 holes to ream out using the tip cleaners. You drill a hole in the welch plug then use an angle awl to pry it out. Be very careful you only drill a hole and not into the body of the carb, the drill bit will give awful suddenly and plunge into the carb. Stay to the right and down.
Same directions as above, Take the carburetor off the engine and apart, but now you will remove the welch plug found on the side of the carb. IMO, you really need to remove this one welch plug. There's a larger welch plug on the bottom of the carb inside the fuel bowl which is unnecessary to remove. This passageway leads into the primer nipple and into the main jet.
Use the carb cleaner to spray every orifice, then use the correct size tip cleaner, again in every orifice. Cleaning these 3 holes really work. It is so important.
Method 3 - materials needed, same as above including the welch plug but now you are using a 1 gallon solvent dip tank chemical with a lowering basket such as Berryman's ChemDip $28 or NAPA's equivalent $23, folding set of welding torch tip cleaners. For years I've been using Berryman's ChemDip and for the most part it's been terrific. Upon recommendations from this Forum I recently bought NAPA's equivalent but have not used it yet. However the dip tank does not work on every carburetor but most. I used this method for years and got wonderful results however, these dip tanks are terrific. I did get some failures until Method 4. See my comment in the next, Method 4 where they don't work! Other than Method 4, this is the way to go.
In Method 3 you take the carb apart, removing the infamous and scary welch plug, letting the carb soak in the solvent dip tank for 20 minutes to 4 hours depending how bad the varnish is on the carb. After this it starts to discolor the aluminum to a dark color.
Remove and use the tip cleaners, then submerge in a bucket filled with water, blow out with an air compressor, spray with the carb cleaner as it supposedly retards or prevents the discoloration of the aluminum, let air dry, put back together and install.
Method 4 - same as all above but now you are adding an ultrasonic cleaner. A bottom good one with a heater will cost you $400-$500.
In the past I let the carb sit in the Berryman ChemDip in the Ultrasonic Cleaner (UCl) for 30 minutes then turned the UL for 30. If the carb was really dirty I let it sit for another 30 then turned the UCl on for 30 minutes. What I plan to do this year, let the carb sit in the NAPA dip tank cleaner then run it in the Berryman ChemDip in the UCl.
I think the ULc is terrific but the dip tank is really good and successful in most cases.
You do everything as in Method 3, take the carb apart, remove the welch plug, let sit in the dip tank solution, then use the ULc, remove, use the tip cleaners, submerge in water, blow out with an air compressor, let dry, put back together and install.
I have 2 examples of where the ULc saved the carb.
A push lawnmower would not start or run except using starting fluid then it died each time. I removed the carb, took it apart, soaked in Berryman's ChemDip, put back together, installed, started and ran but surged very badly. Shortly after I got the ULc, I removed the carb, took it apart and put in the ULc and when installed, the lawnmower ran smoothly.
Another example, a MTD snowblower with a 5hp Tecumseh engine I was asked by a neighbor to work on, it started and ran "great", no surging, smoothly, but only ran on full choke, turn it one notch off full choke and the engine died. I felt in a snow the engine would have had no power, no guts under load but the homeowner had been using it??? he said.
I took the carb off, apart, I did not remove the welch plug, and soaked in the ChemDip, then reinstalled the carb on the engine. Now the engine ran great, no surging but I had to have it on one choke notch to run at all, an improvement. On no choke the engine would immediately die. I shared the snowblower with this neighbor using it for one year in several snowstorms, and in one or two 25" snows. It ran great, but could never take it off one choke.
The following year I got the ULc and asked the neighbor to bring his snowblower back to me. I took the carb off, apart, again I did not remove the welch plug, and put it in the ChemDip in the ULc! Started on the first pull and once warmed, ran on NO CHOKE, the way it is suppose to run. Again, I shared the snowblower with the neighbor using it again another year and had several snows to use it, again another 25" snow. It worked well and always on no choke.
Last edited by JLawrence08648; 02-06-2017 at 05:08 PM.
Reason: Added several fuel cleaners